Cap for a writing instrument



FIG. 1 is a front elevational view of a cap for a writing instrumentshowing my new design;

FIG. 2 is a left side elevational view, the right side being a mirrorimage thereof;

FIG. 3 is a rear elevational view;

FIG. 4 is a top plan view;

FIG. 5 is a bottom plan view; and,

FIG. 6 is a top, right front perspective view thereof.

The ornamental design for a cap for a writing instrument, as shown anddescribed.